Constant impedance high resolution phase shifter



- June 22,;15970 .-G, R,.LE EF ErAL y v ,3,516,028

v CONSTANT I rIa'PEDANcE HIGH 'RESOLUTION PHASE sHIFTER I FiledrJunre14, lse

E INVENTORS,

GEORGE R. LEEF a #Ev/ygl G. NOR/DUN.

A T TORNE YS United States Patent O j 3,516,028 CONSTANT IMPEDANCE HIGHRESOLUTION i PHASE SHIF'I'ER George R. Leef, Morris County, NJ., andHenry G.

Nordlin, Allen County, Ind., assignors, by mesne assignments, to theUnited States of America as represented by the Secretary of the ArmyFiled June 14, 1968, Ser. No. 737,131 Int. Cl. H03h 7/30 U.S. Cl. 333-3110 Claims ABSTRACT OF THE DISCLOSURE A continuously variable delay lineis disclosed. The delay line features a plurality of sections of coaxialline electrically connected in series but physically arranged inparallel around a central adjusting mechanism. The delay time is variedby moving a plurality of -ferrite tubes axially from a position whereone tube is outside the outer conductor of each coax section to aposition where one tube occupies the space between the inner and outerconductor of each coax section.

BACKGROUND OF lNVENTION 'Ihe present invention relates generally todelay lines; and more particularly to low-loss, continuously variable,phase rShifters for use at high power RF frequencies. Until theinvention of a'low-loss continuously variable delay line by HelmutBrueckmann, Pat. No. 3,219,950, assigned to the assignee of thisinvention, low-loss delay lines tended to be'heavy and Vbulky and manyof the prior art delay lines, due to particular design features, werenot entirely satisfactory for applications involving high RF power.This'invention is an improvement of the basic van'- able delay linedisclosed in the above cited patent to Helmut Brueckmann.

SUMMARY It is therefore, van object of this invention to provide acontinuously variable phase shifter.

Another object of this inventionisto provide a relatively small andcompact low-loss delay line for use at high power RF frequencies.

A still further object of this invention is to provide a variable delayline constructed in a compact structural unit with an indicator forreading the time delay introduced for a given setting of the delayadjustment means.

DESCRIPTION OF DRAWINGS DESCRIPTION OF PREFERRED EMBODIMENT The phaseshifter shown in the drawing utilizes six sections of exible coax line.The coax sections 28 are arranged physically in a circular fashionaround a common center. While the coax sections are physically arrangedin parallel, they are connected electrically in series by means of thestraps 20 shown in FIG. 5. Straps 20 or any the line ice suitableconnectors are used at both ends of the device to completetthe seriescircuit. These electrical connections are protected by means of the endcaps 23. End caps 23 also provide shielding. The body or main housing ofthe phase shifter consists of the two sections 25 and 26. Both sections25 and 26 are solid aluminum blocks that have been machined out toaccommodate coaxial lines 28 and other parts to be described in detaillater. Body sections 25 and 26 are held together by long bolts 27. Themain housing is fabricated in two sections in the manner just describedto facilitate assembly of the phase shifter.

Each of the six coax sections 28 can be considered to be separated intotwo pieces. The iirst piece comprises an outer conductor 21 and an innerconductor 18. The second piece of each coax section 28 has an innerconductor labelled 16 in FIG. l. Inner conductor 16 has the samediameter as outer conductor 21 of the first piece. Outer conductors 21are connected to the main body or housing by means of the rings 22 andthe ribs 24. Ribs 24 provide short connections to each outer conductor21 to the main housing sections 25 and 26. Outer conductor 21 and innerconductor 18 are discontinuous at this point. The outer conductor of thesecond piece of each coax is section 26 of the main housing.

The inner conductor 18 of each of the six coax sections is electricallyconnected, by any suitable means such as solder, to the inner conductor16. Inner conductor 16 is supported by outer conductor 21 by means ofthe insulating ring 17.

From the foregoing description it is apparent that each coax section 28can be considered as consisting of two parts, one part having a largerdiameter than the other part. The small diameter part having an outerconductor 21. The larger diameter part consists of piece 16 and housingsection 26.

As shown in the drawing the smaller diameter part of each coax section28 is surrounded by a tubular member 29. Tubular member 29 is a hollowferrite cylinder constructed of alternate hollow cylindrical discs of aferrite material 1 and a ceramic material 2 bonded together by anysuitable means. Of course, ceramic discs 2 can be replaced by ferritediscs or tubular member 29 could be made from a solid piece of ferritethat has been machined out to form a hollow cylinder. Each tubularmember 29 has a longitudinal slot 19 to allow it to slide past rib 24.Another function of slot 19 is to reduce the effective relativepermeability of the ferrite to match it to the effective relativedielectric constant of the ferrite for the purpose of making thecharacteristic impedance a constant, whether the ferrite is inserted orwithdrawn.

The six tubular members 29 are connected by means of Y the rings 10 andthe ribs 11 to a micrometric lead screw 3 having 10 threads to an inch.Lead screw 3 rotates in the bearings 13 and is turned by means of yaknob 4.

The position of lead screw 3 is determined by an indicator as shown inFIGS. 1 and 2. The indicator consists of a dial 5 with engraved markingscorresponding to .00f1 inch movement of members 29, an index 6 andGeneva drive type counting dials 8 yand 9. If desired, the indicator canbe calibrated to read time delay directly. The input and outputconnections, 14 and 15 respectively, are located next to the indicator.

' The phase shifter constructed in the manner shown in the drawingprovides a continuously variable time delay of up to 30 nanoseconds,from 7 nanoseconds to 37 nanoseconds. When tubular members 29 are in theposition shown in the drawing no time delay, other than the basic timedelay of the device, is introduced. In this position the members 29 areoutside of the outer conductors 21 of coax sections 28. When members 29are moved by means of screw 3 and knob 4 to a position to the left ofthe position shown, the time delay is varied. In this position, members29 occupy the space between the inner and outer conductors of coaxsections 28. The outer conductor for all six coax sections being housingsection 26 in this area. The time delay increases-as the members 29 aremoved from right to left. The time delay introduced is a maximum whenmembers 29 occupy all the space between housing section 26 and parts 16of coax sections 28. In other words, the time delay is a maximum whenmembers 29 are moved completely to the left of the position shown in thedrawing.

What has been described above is a preferred embodiment of theinvention. Various changes and modifications can be made to thepreferred embodiment Without departing from the spirit and scope of theinvention as defined in the claims. For example, rigid coax sectionshaving tubular conductors can be used for coax sections 28 instead ofthe flexible type coax. If rigid coax is used the housing can be ahollow cylinder of brass or aluminum instead of the machined outaluminum block shown; because no extra support is needed for the coax.Also, more than six coax sections can be used.

What is claimed is:

1. A constant impedance high resolution phase shifter comprising:

a plurality o-f coaxial sections each havin-g an inner and outerconductor, each of said coax sections being discontinuous at itsmid-point along the length of the section thereby forming a first halfand a second half, the diameter of the inner conductor of said secondhalf of each coax section being the same size as the diameter of theouter conductor of said first half of each coax section;

a plurality of hollow ferrite cylinders being equal in number to saidplurality of coax sections and being approximately one-half as long assaid coax sections, one of said coax sections being inserted into eachof said ferrite cylinders;

a generally cylindrical shaped housing;

means to secure said coax sections inside said housing in such a mannerthat said coax section-ferrite cylinder combinations form a ring havinga diameter slightly smaller than the diameter of said housing;

means inserted inside said housing and secured to said ferrite cylindersfor axially moving said ferrite cylinders along said coax sections;

means positioned at said mid-point for connecting said! inner conductorof said first half of each coax section to its associated innerconductor of said second half;

means for connecting the outer conductor of said first half of all ofsaid coax sections to said housing;

means for electrically connecting said coax sections in series;

means for applying an input signal to said coax sections; and,

means for obtaining an output signal from said coax sections.

, 2. A constant impedance high resolution phase shifter as defined inclaim 1 wherein said plurality of coax sections is vsix in number.

3. A constant impedance high resolution phase shifter 5 as defined inclaim 2 wherein said housing comprises two sections, 'each section beinga solid block of aluminum that has been machined out to accommodate thecoax sections, the ferrite cylinders and said means for moving saidferrite cylinders.

4. A constant impedance high resolution phase shifter as defined inclaim 3 wherein said means to axially move said ferrite cylindercomprises a micrometric screW having a knob at one end to facilitatevthe turning of said screw.

5. A constant impedance high resolution phase shifter as defined inclaim 1 wherein said coax sections are rigid.

6. A iconstant impedance high resolution phase shifter as defined inclaim 1 wherein said coax sections are flexible.

7. A constant impedance high resolution phase shifter as defined inclaim 5 wherein said housing is a hollow cylinder of electricallyconductive material.

8. A constant impedance high resolution phase shifter as defined inclaim 1 'wherein indicator means for indicating the position of saidferrite cylinders along the length of said coax sections is mounted onsaid housing.

9. A constant impedance high resolution phase shifter as defined inclaim 1 wherein said ferrite cylinders are made of alternate hollowdiscs of a ferrite material and a ceramic material.

10. A constant impedance high resolution phasev shifter comprising aplurality of coax sections so designed that the effective diameter ofeach of said coax sections is greater for one half of its length than itis for the other half;

a plurality of ferrite cylinders; and

means connected to said cylinders for selectively moving said cylindersto a position where one of said cylinders is outside the outer conductorof each of said coax -sections to a position where one said cylinder isbetween the inner and outer conductor of each of said coax sections.

References Cited UNITED STATES PATENTS 3,219,950 11/1965 Brueckmann333-97 X 3,440,573 4/1969 Buuer 333-31 HERMAN KARL SAALBACH, PrimaryExaminer M. INUSSBAUM, Assistant Examiner U.S. Cl. X.R.

